Showing papers on "Atomic layer deposition published in 1996"
TL;DR: In this article, bis-methylcyclopentadienyl nickel (Ni(CH3C»H4)2) and hydrogen peroxide (H202) were used for controlled growth of amorphous nickel oxide films by sequential surface chemical reactions.
Abstract: Nickel oxide films have been fabricated by various physical and chemical vapour deposition (CVD) techniques such as reactive sputtering [1] and plasma-enhanced chemical vapour deposition [2] because their chemical stability as well as their optical and electrical properties are excellent. If the fabrication technology could lead to growth on an atomic scale, it would be rauch more interesting also for applications to soft X-ray multilayers and neutron optics because compound multilayer structures consisting of NiXx (X = C, N, dry air) layers have been the focus of recent attention [3]. In recent years, atomic layer deposition of A1203 [4-7], TiO2 [8, 9] and multilayers based on A1203/TiO2 [10] by sequential surface chemical reactions has been reported. This deposition technique could be used to sequentially dose a surface with appropriate chemical precursors to promote surface chemical reactions that are inherently self-limiting. The selflimiting nature of the surface reactions enables precise control of the thickness of the deposited layers on an atomic scale and gives rise to homogeneous films on large areas. In this work, bis-methylcyclopentadienyl nickel (Ni(CH3CsH4)2) and hydrogen peroxide (H202) were used for controlled growth of amorphous nickel oxide films by sequential surface chemical reactions, because amorphous structures are suitable for applications to soft X-ray multilayers due to their smooth surface and interface. The experimental setup comprised a stainless steel vacuum chamber with computer-controlled leak and gare valves, a capacitor manometer and a substrate holder connected to a heater. The substrate was cut from a (100)-orientated Si wafer. As vapour sources, high purity bis-methylcyclopentadienyl nickel (Ni(CH3C»H4)2; Trichemical Laboratory Inc.) and H 2 0 2 w e r e used. As shown in Fig. 1, the vapour pressure of Ni(CH3CsH4)2 is high among those of nickel compounds [11], which makes it rather easy to u s e . H 2 0 2 w a s prepared by vacuum distilling
138 citations
TL;DR: In this paper, a simple molecular description for chemisorption and surface reactions is suggested and shows that both reaction steps have an effect on the growth rate of atomic layer deposition.
128 citations
TL;DR: In this article, thin (2-10 nm) silicon nitride films have been grown by repetitive plasma nitridation of Si using a NH3 remote plasma and deposition of Si by a SiH2Cl2 thermal reaction.
Abstract: Thin (2–10 nm) silicon nitride films have been grown by repetitive plasma nitridation of Si using a NH3 remote plasma and deposition of Si by a SiH2Cl2 thermal reaction. The deposition rate is self‐limited at nearly half‐molecular layer (ML) per one deposition cycle. The process window for the half‐ML/cycle of growth has been investigated with respect to the NH3 plasma power, SiH2Cl2 exposure time, and substrate temperature. The thickness fluctuation of the film over a 2 in. wafer is within measurement accuracy of the ellipsometer (± 1.9%) for the atomic layer controlled film while it is ± 8.5% for all the remote‐plasma chemical vapor deposition film.
127 citations
TL;DR: In this article, the atomic layer epitaxy (ALE) approach is used to create conditions for monoatomic layer buildup through saturated surface reactions, which has been successfully applied in commercial manufacturing of thin film electroluminescent displays.
107 citations
TL;DR: In this article, a conformal coatings was successfully applied to porous silicon layers, and the influence of the porous substrate structure on the deposition parameters was analyzed from the viewpoint of formation mechanism, growth rate, and layer composition.
Abstract: The deposition of conformal coatings into porous silicon layers was successfully demonstrated. Tin oxide films were formed from SnCl 4 and H 2 O precursors by atomic layer epitaxy. The influence of the porous substrate structure on the deposition parameters was analyzed from the viewpoint of formation mechanism, growth rate, and layer composition. The SnO x covered porous substrates were characterized by means of Rutherford backscattering, secondary ion mass spectrometry, cross-sectional transmission electron microscopy, and ellipsometry. The mesoporous structure of the Si substrate uniquely determines the gas-phase diffusion and physisorption of the precursors. The processing parameters favoring chemisorption are more critical for porous silicon than those for a flat surface. Even a small decrease in the deposition temperature results in a considerable increase in the growth rate through gas-phase reactions, and the process becomes chemical vapor deposition-like. Conformal step coverage was obtained on extremely high (140 :1) aspect ratio pores if the deposition conditions were chosen such that chemisorption was the growth rate determining step in the process.
86 citations
TL;DR: In this paper, atomic layer growth of polycrystalline films of pure rutile, pure TiO 2 -II, or a mixture of them could be obtained at the same growth temperature (400°C) and at different TiCl 4 vapor pressure (0.34 Pa) applying different water vapor pressures during the water pulse.
76 citations
TL;DR: In this paper, a high electron mobility of 30 cm2/Vs was obtained for undoped ZnO films only 220 nm thick and the mobility of films was higher than that of films grown by MOCVD.
Abstract: ZnO films have been grown by atomic layer deposition (ALD) using diethylzinc (DEZn) and H2O as reactant gases. Self-limiting growth occurred at substrate temperatures ranging from 105 to 165° C. Self-limiting growth was also achieved when the flow rates of DEZn and H2O were varied. It was found that the orientation and surface morphology of the films were strongly dependent on the substrate temperature. A high electron mobility of 30 cm2/Vs was obtained for undoped ZnO films only 220 nm thick. The mobility of films was higher than that of films grown by MOCVD.
66 citations
TL;DR: In this article, the surface processes during the atomic layer deposition (atomic layer epitaxy) of tantalum oxide thin films from TaCl5 and H2O were studied, and the mechanisms of suboxide growth and etching in the continuous precursor flow was evaluated on the basis of the measurement results and thermodynamic probability for different reactions.
51 citations
TL;DR: In this article, the film formation mechanism during the alternating vapor deposition polymerization was studied by monitoring the change in the amount of adsorbate during the deposition, and a multilayer polyamide thin film with a layered structure like an Langmuir-Blodgett film was obtained by use of the alternating-vapour-polymerization method, similar to the atomic layer epitaxy method.
47 citations
TL;DR: In this paper, a three-stage method using a coevaporation apparatus was used to fabricate ZnO/ZnSe/CIGS thin film solar cells with about 10 nm thick ZnSe buffer layer.
Abstract: Cu(InGa)Se{sub 2}(CIGS) thin film absorbers were fabricated by a three-stage method using a coevaporation apparatus. As a Cd-free buffer layer, ZnSe, In{sub x}Se{sub y} and ZnIn{sub x}Se{sub y} and ZnIn{sub x}Se{sub y} buffer layers have been deposited on the CIGS absorber continuously in the same apparatus. Atomic layer deposition (ALD) was employed as a growth technique for ZnSe. This technique offers a good thickness control as well as a good surface coverage. By irradiating with a solar simulator, all the solar cell parameters increased drastically for the first 50 minutes of the irradiation and then saturated at longer irradiation times. This phenomenon did not appear for the cells with a CdS buffer layer. The best efficiency of ZnO/ZnSe/CIGS thin film solar cells with about 10 nm thick ZnSe buffer layer was 11.6%. On the other hand, ZnO/In{sub x}Se{sub y}/CIGS thin film solar cells showed very stable characteristics under the light illumination, and initial measurements show an efficiency of 13.0%.
30 citations
TL;DR: In this article, an optical method for in situ diagnostics of atomic layer deposition, based on the measuring of the reflectivity of a p-polarized light in fully transparent systems, is proposed and analyzed by using a classical four-phase approximation.
Patent•
27 Mar 1996
TL;DR: In this paper, a self-aligning layer is formed over a barrier layer prior to deposition of a conducting film thereover, which enhances the reflectivity of the films by improving the crystal structure in the resulting film and provides improved electromigration performance by providing crystal orientation.
Abstract: The present invention relates generally to an improved apparatus and process to provide a thin self-aligning layer prior to forming a conducting film layer thereover to improve the film characteristics and deposition coverage. In one aspect of the invention, a dielectric layer is formed over a conducting or semiconducting layer and etched to form an aperture exposing the underlying conducting or semiconducting layer on the aperture floor. An ultra-thin nucleation layer is then deposited by either vapor deposition or chemical vapor deposition onto the field of the dielectric layer. A CVD metal layer is then deposited onto the structure to achieve selective deposition on the floor of the aperture, while preferably also forming a highly oriented blanket layer on the field. In another aspect of the invention, a thin, self-aligning layer is formed over a barrier layer prior to deposition of a conducting film thereover. It is believed that the self-aligning layer enhances the reflectivity of the films by improving the crystal structure in the resulting film and provides improved electromigration performance by providing crystal orientation. The process is preferably carried out in an integrated processing system that includes both a PVD and CVD processing chamber so that once the substrate is introduced into a vacuum environment, the process occurs without the formation of oxides between the layers.
Patent•
NEC1
TL;DR: In this article, a method of forming a thin semiconductor film including an impurity for obtaining a conductivity includes the step of depositing a thin amorphous silicon film by chemical vapor deposition using silane as a deposition source gas at a deposition rate of at least 3 nm/minute while introducing the impurity.
Abstract: A method of forming a thin semiconductor film including an impurity for obtaining a conductivity includes the step of depositing a thin amorphous silicon film by chemical vapor deposition using silane as a deposition source gas at a deposition rate of at least 3 nm/minute while introducing the impurity, and the step of crystallizing the deposited thin amorphous silicon film by annealing.
13 May 1996
TL;DR: In this paper, the nucleation and growth of the CdS buffer layer (chemical bath deposition) on CIGS thin films was observed using the surface-specific methods of atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE).
Abstract: In this work, the nucleation and growth of the CdS buffer layer (chemical bath deposition) on Cu(In,Ga)Se/sub 2/. (CIGS) thin films was observed using the surface-specific methods of atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE). The AFM images show islands at short deposition times (<30 s) whereas XPS measurements do not register any sulfur on these surfaces. The authors postulate that Cd(OH)/sub 2/ precipitates out of the basic deposition solution while rinsing it off the CIGS surface, thus creating the islands. All methods used here indicate the onset of bulk CdS growth after about 30 s deposition time. According to the AFM images, the entire CIGS surface seems to be covered within 1 min deposition. This is confirmed by SE, which shows bulk layer growth after 1 min; it increases at about 0.4 nm/s after the induction phase.
TL;DR: In this paper, the effects of oxidants on the deposition characteristics and dielectric properties of the thin films are mainly tested, and the results showed that O2, N2O and O2+N2O gases are used as the oxidants and the films with Ti-rich and Sr-rich compositions are obtained when O2 and N 2O is used.
Abstract: SrTiO3 thin films are deposited by a liquid source metal-organic chemical vapor deposition (MOCVD). The effects of oxidants on the deposition characteristics and dielectric properties of the films are mainly tested. O2, N2O and O2 + N2O gases are used as the oxidants and the films with Ti-rich and Sr-rich compositions are obtained when O2 and N2O is used, respectively. Deposition of thin initial layer under O2 atmosphere is very effective to obtain large dielectric constant of the SrTiO3 thin film when the main layer is deposited under O2 + N2O atmosphere. The dielectric constants of 40 nm thick SrTiO3 films with thin O2, N2O initial layers and without the initial layers are 235, 145 and 210, respectively.
13 May 1996
TL;DR: In this article, a microwave induced remote plasma (MIRP)-hydrogenation of thin film silicon (TFSi-) solar cells was studied in the presence of an oxide during the hydrogenation.
Abstract: Common features of thin film silicon (TFSi-) solar cells hydrogenated in a microwave induced remote plasma (MIRP) are studied. The thin films were epitaxially grown on ribbons and multicrystalline silicon (mc-Si). Optimal hydrogenation renditions are presented in relation to the sample conditions such as the surface passivation, the active carrier concentration in the epitaxial layer and the substrate material. The MIRP-hydrogenation is studied in the temperature range of 350-415/spl deg/C. A high passivation efficiency is observed at 400/spl deg/C for all substrates in spite of an unfavourable hydrogenation regime at 375/spl deg/C. In the absence of an oxide during the hydrogenation, an optimal hydrogenation time of 1 hour is observed irrespective of the substrate used. This optimal hydrogenation time is a consequence of the interaction between the incoming atomic hydrogen and the boron dopant in the epitaxial layer.
TL;DR: In this article, the authors investigated a new reaction pathway for atomic layer deposition of Si on various metal and semiconductor substrates using a novel organosilicon compound, Si(C6H10)2, which has a central Si atom with two identical 5-fold hydrocarbon rings.
TL;DR: In this paper, heavily in situ boron doped SiGe layers with 30% Ge were grown by low pressure rapid thermal chemical vapour deposition (LP(RT)CVD).
Abstract: In strained Si a−x Ge x heterojunction internal photoemission (HIP) photodiodes the spectral response can be tailored over a wide wavelength range by varying the Ge content. In this paper heavily in situ boron doped SiGe layers with 30% Ge were grown by low pressure rapid thermal chemical vapour deposition (LP(RT)CVD). The detectors exhibit a cut-off wavelength of 8.5 μm. A delta-like P peak, incorporated by atomic layer deposition technique, shifts the cut-off to shorter wavelengths. This shift is related to an increase of the barrier height at the SiGe/Si interface caused by the narrow n + -doped layer in agreement with device simulation. In this way the trade off between critical film thickness for high Ge content film growth and absorption depth for proper detector response can be overcome.
13 May 1996
TL;DR: In this article, the average grain size of CdS films is established at early deposition times, and complete conformal coverage is observed at low thickness values, and the bandgap values depend mainly on substrate structure.
Abstract: CdS films have been deposited by solution growth on SnO/sub 2/ and glass substrates. Nucleation on SnO/sub 2/ occurs at early deposition times, and complete conformal coverage is observed at low thickness values. The average grain size of the CdS films is established at these early times. In films deposited on glass substrates, nucleation is slower and occurs through 3-dimensional islands that increase in size and number as deposition proceeds. Optical measurements show that the bandgap values of CdS films deposited on SnO/sub 2/ depend mainly on substrate structure. Hydrogen heat treatment does not affect the surface morphology of the samples, but decreases bandgap values.
TL;DR: In this paper, thin films of silicon carbide have been prepared by plasma enhanced chemical vapour deposition using Si(Si(CH3)3)4 as a precursor, which is stable against moisture and air and has a high vapour pressure.
02 Nov 1996
TL;DR: In this paper, the role of stochastic wandering of electrons near the points where they deposit their charge is discussed for charge deposition near inhomogeneities in a target and an analysis of the mechanism of charge deposition distribution shaping in small-size spatial regions of a target is made.
Abstract: Charge deposition in targets consisting of materials with atomic numbers from 6 to 92 irradiated by normally impinging broad electron beams with energies from 0.1 to 10 MeV are studied. Using the modification of trajectory rotation method [Nucl. Instr. and Meth. B 108 (1996) 276] for the charge deposition calculations, the data on primary electron charge deposition distributions in target are obtained. An analysis of the mechanism of charge deposition distribution shaping in small-size spatial regions in a target is made. The role of stochastic wandering of electrons near the points where they deposit their charge is discussed for charge deposition near inhomogeneities in a target. In is noted that neglect of the electron stochastic wandering can lead to the artifacts in calculations and erroneous conclusions concerning charge deposition near interfaces in heterogeneous targets.
21 Jul 1996
TL;DR: In this article, a plasma assisted vacuum deposition of TiN and TiO/sub x/ films is performed using four vacuum arc evaporators and four hot-cathode-arc plasma generators.
Abstract: Plasma-assisted vacuum deposition of TiN and TiO/sub x/ films is performed using four vacuum arc evaporators and four hot-cathode-arc plasma generators Film deposition on substrates of total area 6 m/sup 2/, with the workpiece having dimensions of 1/spl times/16 m, is completed in one cycle The arc parameters in the process of film deposition are typically as follows: the vacuum arc current and voltage are 100 A and 30 V, respectively, and the hot-cathode arc current and voltage are 20 A and 50 V, respectively The deposition of a TiN film on a metal takes 50 min, while the TiN or TiO/sub x/ film deposition on a dielectric occurs within 20 min
13 May 1996
TL;DR: In this paper, a self-limiting growth was observed for substrate temperatures from 105 to 165/spl deg/C, even when the flow rates of DEZn and H/sub 2/O were varied.
Abstract: ZnO films have been grown by atomic layer deposition (ALD) using diethylzinc (DEZn) and H/sub 2/O as reactant gases for solar cell applications. Self-limiting growth was observed for substrate temperatures from 105 to 165/spl deg/C, even when the flow rates of DEZn and H/sub 2/O were varied. The film thickness was very uniform, which was greatly improved compared to films grown by MOCVD. The orientation of ZnO films depends strongly on the substrate temperature. A high electron mobility of 30 cm/sup 2/ N/spl middot/s is obtained for undoped 220 nm thick ZnO films, which is higher than that of films grown by MOCVD.
DOI•
01 Jan 1996
TL;DR: Growth and Characterization of Thin Film Electroluminescent Devices Fabricated Using Atomic Layer Epitaxy as mentioned in this paper, is a case study of the use of atomic layer epitaxy.
Abstract: Growth and Characterization of Thin Film Electroluminescent Devices Fabricated Using Atomic Layer Epitaxy
13 May 1996
TL;DR: In this article, the authors have discovered one of the major causes of thickness nonuniformities in large-area deposition of hydrogenated amorphous silicon, a-Si:H, on glass.
Abstract: The authors have discovered one of the major causes of thickness nonuniformities in large-area deposition of hydrogenated amorphous silicon, a-Si:H, on glass The influence of a gap between the substrate and the grounded electrode on the deposition rate is presented At a gap of 085 mm and at an RF excitation frequency of 40 MHz, the reduction of the deposition rate is 15%, whereas at 60 MHz it amounts to 25% The deposition-rate reduction is described in terms of a reduced voltage across the sheath at the substrate electrode The observed effects stress the importance of proper substrate-to-electrode attachment when the VHF glow-discharge technique is used for deposition of solar cells on large areas
01 Jan 1996
01 Jan 1996
TL;DR: In this paper, a self-limiting growth was observed for substrate temperatures from 105 to 165 "C, even when the flow rates of DEZn and H20 were varied.
Abstract: ZnO films have been grown by atomic layer deposition (ALD) using diethylzinc (DEZn) and H20 as reactant gases. Self-limiting growth was observed for substrate temperatures from 105 to 165 "C, even when the flow rates of DEZn and H20 were varied. The film thickness was very uniform, which was greatly improved compared to films grown by MOCVD. The orientation of ZnO films depends, strongly on the substrate temperature. A high electron mobility of 30 cm2N.s is obtained for undoped 220 nm thick ZnO films, which is higher than that of films grown by MOCVD.
01 Jan 1996
TL;DR: Andrade et al. as discussed by the authors proposed a model for the integration of Fisica in the CETEC of Cidncias Exatas Universidade Federal de Minas Gerais.
Abstract: F M Matinaga. L A.Cury, E C Valadarcs, M.V.B Moreira, W.N.Rodrigues and A.G de Oliveira, J hl C Vilclaf. M.S.Andrade:. J.A.Slusst Lkpartamento de Fisica lnstituto de Cidncias Exatas Universidade Federal de Minas Gerais. Caixa Postal 702. 30161-970 Belo Horizonte, Minas Gerais, Brazil. ' I:tinda@o Centro 'Tecnologico de Minas Gerais CETEC. AV. JosC Cindido da Silveira, 2000 Horto, 3 I 170-000 Belo Horizonte. Minas Gerais, Brazil.